The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Hard disk drives (HDDs) include magnetic recording surfaces called platters and read/write heads that read and write data on the platters. Before data can be written on the platters, a servo pattern is recorded on the platters. The read/write heads use the servo pattern for positioning when reading and writing data on the platters.
Modern HDDs use a self-servo-write (SSW) system to write the servo pattern. The SSW system uses the read/write heads of the HDDs to write the servo pattern. The SSW system writes the servo pattern as follows. First, the SSW system writes seed wedges on a blank disk. Then the SSW system uses the seed wedges for positioning and writes servo spirals. Specifically, the SSW system tracks angular and radial position of the disk by sensing the seed wedges and writes the servo spirals. The SSW system writes the seed wedges and the servo spirals using signals of different frequencies.
Thereafter, the SSW system writes the servo pattern based on the servo spirals. Specifically, the SSW system uses the servo spirals for tracking disk position and writes the servo pattern. For example, the SSW system tracks disk position using the servo spirals and uses a zone servo SSW system to write the servo pattern including concentric servo wedges. Subsequently, user data can be written on the platters using the servo pattern as a reference for positioning the read/write heads.